ETAS
Hardware Description
FETK-T3.0 - User’s Guide
28
4.9.2
Design Recommendations
• Debug and trace connectors should be placed as close to the microcon-
troller as possible
• If a pull down resistor is present on the line /TRST, the ECU must use a
value no smaller than 100K ohm as shown in Fig. 4-8 on page 26.
• PCB trace lengths should be as short as possible for the TMS, TRST,
TCK, TDI & TDO signals
• If any JTAG signals are also routed to a 2nd connector (Forked/Split or
T’d), It is recommended to add zero ohm jumpers in line so the signal T
can be broken
• PCB trace lengths should be as short a possible for the TX0...3_P,
TX0...3_N, ClockP, and ClockN signals
• PCB trace lengths should be matched for the differential pairs TX0...3_P
and TX0...3_N. PCB trace lengths should also be matched for the differ-
ential pairs ClockP and ClockN
• It is not recommended to T (fork/split) any Aurora Trace PCB signals
• All signals on the ETAN2 cables are 50 ohm impedance except the
Aurora Trace signals (1, 3, 7, 9, 13, 15, 19, 21, 26, 28), it is recommended
to match the PCB impedance to the cable impedance
• Aurora Trace signals on the ETAN2 cables are 100 ohm differential pairs
(1 & 3, 7 & 9, 13 &15, 19 & 21, 26 & 28), it is recommended to match the
PCB impedance to the 100 ohm cable impedance